Scleroderma is a debilitating disease characterized by immune system activation and autoimmunity, small-vessel vasculopathy, and fibrosis of the skin, lungs and other organs. It affects approximately 100,000 people in the US, mostly women. The major cause of morbidity and mortality in scleroderma is pulmonary fibrosis (55,56), i.e. the excessive accumulation in the lungs of extracellular matrix (ECM) proteins, particularly collagen. The cell type most frequently associated with fibrosis is the myofibroblast. Myofibroblasts are fibroblasts that exhibit certain muscle-like properties: they are contractile and they contain the marker protein α-smooth muscle actin (ASMA) (5). There are few myofibroblasts in normal lung tissue. In contrast, there are many more fibroblasts in fibrotic lung tissue than in normal tissue. Many of these fibroblasts are myofibroblasts, and collagen deposition in fibrotic lung tissue routinely occurs at sites rich in myofibroblasts. Thus it is clear that these cells play a key role in the genesis of fibrotic lesions.